SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '326747040f29420cd83ee1f6b87ce01b7985c43876cae91191d0bdedcc39c497' 
  AND token = '2KaNlN3xZPnmLgtzXDXWa2cxrRl2spktPNyHSYPFrJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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