SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c29f4db3df0b4f25fb87a95ea7b389a95e945f139dac8a0822fef5ab76186687' 
  AND token = '61zXLxeac0NbPDxgmYdh7papF0LtJR1R0JcAFzTIk7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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