SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78a1c705f10329bd290f8a8351a0c9e8b8350e24e25d89a0c82b04897c065f8a' 
  AND token = 'B6qNiTlbBHYOSk+TJOfue5NQ60YEJLxANYGY7Lepv18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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