SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cc9d494ceb0e498acc43255fb301b53e34e4705d2652c781752e04298300824' 
  AND token = '9jzqXebe1vWEZSTiMFDK5zWqTxv7ImIbdDsZgkMpVoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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