SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4371968573ea2d338f800d38966798ce477de4080cd000700df1c63e22b08fe8' 
  AND token = 'PQxmUpgLJ+jtffbTpdeWIMawYF21YvbZS/qTVv93UoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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