SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6fa99db160ce1b286c04cf987350a90c7b80a83c7a5150c1f7b3e8032a34c3e' 
  AND token = 'KuxDEhgc+KIBwVeyAG7Kzz0txAZCiz6u3YZUlq26StQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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