SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '333b0fc1019601242547440fd5121658f67b3a9a47156dbccf42e4c2a8fff68f' 
  AND token = 'EQTMdgYE0+q5xHK8w0UKPT5ZCjkz5NAOrV4vVkx7tjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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