SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52b2dd47015db681cc036796607efa64f848d18c45630e6e689f2eadd146bdce' 
  AND token = '5RUdPvLGgMfMPripxoVojjlP0xUreMD8JeuFTvhJZmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00060

JSON explain

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