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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '555afafb0e8a2c19afce5dd88e0a3ce753b22eb1d7dd2bb0d508b9b8eacf9d5c' 
  AND token = 'iVqMez2vefBPwimTTxoPXXcoyzEGI9nyNpgC4veIjwI=' 
  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"
    }
  }
}