SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c616ff5561a79455b532f92693835da624b756c7b98eafcf684226e382950e7f' 
  AND token = 'RW9BYqzAb263v2p9fw3TeKXdVrULpVs5Fh1QZfbIceI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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