SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc301f99e205f8528e69a0604a016df101434ede5f4130da09eee3868cef384b' 
  AND token = 'NZApM4ON+kRs8Yzt+fbH5HreA+0g8T7jwDnYgHCcb6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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