SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31768b095414f9d0b6d1ec6da283088f445c15745d5225c2955b5dbb722bab21' 
  AND token = 'xLWcJj73NxHqlydj2A+LKnhXOvkF9eWSlXph/ikkyLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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