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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d397a251a60d9a1967a44a69e9910dea2f2291c0db9fbfb33f1c29a7b48a413' 
  AND token = 'SA9BmNhmOfEPIxU7WFEgTQKB4sC0yZ9zx1ZfqFcAR5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}