SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c75763404aeab130c09a1d08ff84e9824c15c6a24e6226180f44615bcc75f0d' 
  AND token = 'zEEgaDYXALsqglR65HJm21cgoMDzOOsDigk3zjLdpzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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