SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f40444ea4d4338c85726f3c505569e1035baa56fbd0666f1a44fdf00fe171111' 
  AND token = 'OullIBzKVy7/kkgdAEHqToJb9SYcBfOUrqvwrlmRiUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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