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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '566ec6b775cbf13307c4c10bc23dde1e3c2f7ebe8bf6caa3fe1c7016f065a32e' 
  AND token = 'JsOAIRlmXIQWK3jeMigUa10qYGSjR671Qsv+7j8Qs2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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