SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8a494b92509c41616a462108c6df9f053d86fdd808ead67e5857d18ece1171' 
  AND token = 'wKtdXUuqS7+/pssEscEQiCIkmM1xan12RBwEK9toHlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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