SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712d2b8a928837362008be3bdb620aa70acec7b4313edeb6b031638dcb1c33f1' 
  AND token = 'ecwi/0vyYkWoNE8HtvqSkJLlpGmsgJNrsmuZZIos4xY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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