SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57fe793eb3399aba255f1be8c5b0409c4d9443efa775d5c3f6318840bcec05e9' 
  AND token = '/tDjlulXGhzbjkDgznAY/wEUSIge7MVMVQGyEo2VqyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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