SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fff29aded25421b24a872e2d77bb09b958e8510454483e5d0782010c7e29698' 
  AND token = 'qR7AZHWRZxkMFdj9MnG4aqJpwSG2NyinHcKrAhuMP6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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