SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08493234e246e5f58493f979a88673798d0ab4729fac6389987d4dda35c96890' 
  AND token = 'L+W5Iysy4i0KtXcjt3tjZFSJFu/coaid2vXCrPBHpEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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