SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9cc64f923a908d4680f80699f7355577912b88a608dfc8affe8e59a1f9e61dc' 
  AND token = '2XCWXjB4DEmfzma6DNfn0Dnib9Xqamgyo6tUBZLSg9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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