SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e4cedb1bac9faab4f4e33a26a5be1b15a4fe9f2e019b3ae1c070a03021729f7' 
  AND token = 'ns5nBSEBsBSjdxhMLBTitXkAKVxU30LcXcz3u1jEKaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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