SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1b099ec5fc8044ca195143d050950b3912e2b473e67203f9fc8739a18d5244c' 
  AND token = '6ddeQ0WuN2PQNqmyx2dQwNn3uJvAcPfQRAzlE+X75ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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