SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd33bf8a6e506528fb6547a674ebf7714216f9995785fcb9e8191b41655e1256c' 
  AND token = 'J19xJdlz+yjN1bCAb6MMneaoDbT3LrkOS/VdnnFwF3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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