SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8e7b678da047d141a749ced528cc6455282034ecf77aac21fb4e8a224206436' 
  AND token = 'sEffjHRO8YwdTRcxjD5nBIEX6Jj8u/gB0k5GhcCARAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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