SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b826a4d3b5705794375829ef91777c0e8a81f03db27ce2fa7b414d0cb1cb0901' 
  AND token = 'csMCQ4oOsTyL6ttIBhrT5TVHrDccz5e4ECxeEryvYg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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