SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4d8043ef580bba0c2d7a33ebb377931b182775fac6e103e653144abc17dab6d' 
  AND token = 'vongIMpDa9QM0hMJspqe7IvrtyESXiDAtroQg6VibNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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