SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be7c4fe98dad614d137443521795964ad587a953eac2eb4423cbf33964b5deec' 
  AND token = 'tzmbfEHlFQJw2hvz4wlkHXVtISrAwGenj2vGO0hYRCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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