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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd78eec92f087f80d4935467df28b64c62916259a3983afac09b9adf127669625' 
  AND token = 'eoWyTOEdWP6/paeslZ0AQCCUqaUgrJf+tPow+t9uP38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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