SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68b171bf2daf98341c9afaf5e18f3a695990427c89e30088adec1ac45ec174f5' 
  AND token = 'um3WROm5QUAYdW8Ng85lzAQkwNHfMo5DGtCABNTrlMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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