SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36cc1860cf8294a5336079d19da352fe933debe4708c8df96c3458cffb455149' 
  AND token = 'FbfpzELayfEhVuhedYeDe7NBXNVsO9v0vUkGojuTBg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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