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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79b22a8640e6e9ad63b48745ab2f140a651059bccc23ea01ee8a34ffa60a0f3a' 
  AND token = '8lSfxo+cAMtgHqmmaClcu0XtTXX1VQ+m53ShC7WXVnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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