SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'aa515d9706ab913ecc1eb55add1af62b9e1241b45cc9fd77cdd5df06174e3be4' 
  AND token = 'BEaolLwKcjWZus8kHlfLtTTlTqybuOLQg8+dpsrdH7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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