SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd4e849604b686ae4ce10371139ec125ad7a3a93fe4ee15e3814984f6da08593' 
  AND token = 'VnELGVOid5d/koV+URRT6ZDVJEzsK+rPeW8FHOpQ2uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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