SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fde1d6de9bd9828b3a1bf460fd65e6dec67c21d13a03c942452da5daef3b528' 
  AND token = 'd9vPBheAC03/lzXGYLOwr++t5VNXI1HszpnxwnXjEg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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