SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc08431fc732464a019621357185372230bb670f9fea7a99b3c61cb25370892b' 
  AND token = 'MffntmnAY1+ZCkP9Iahq++WukntIIVVL/MDhK80qeB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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