SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4b4c332ab529ea755d738e343502fa6dc082aed2f72f19eb8b3714f425cf46d' 
  AND token = '+NXvQf1Q2uwRc8Bdo6lUvGJfWJ1DPH7qdRGLhxY1Su8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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