SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '39ae1bb34c9a313f69e96f4a5983e8d133fd4fdaf3eb7203c74d17dcfc980a27' 
  AND token = 'gRVL/Om0VxmG4eyxYZOD4PJzyPRnFDiFrVp2X8/jmgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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