SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db742075f8f8cccbc2e66a4e75c965f013231627fd989b397df121d48f5c820e' 
  AND token = 'gCbWhe/dJjQB17itMG9keCGoevZDsslYDZpGTJIJ1v8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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