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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7b47b82410ddf6ed6b038fea8787181264fe4470dacca32aec6ef6f30da6024' 
  AND token = 'uQv8ZAJ+MmGLQgJP/vYuQ+FYcMrsqZcELaS0BouSaHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}