SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '98c2d6f6b47445fe69ac0c9eee118e9aecf7591eeb4975b6f3c7a2934810b5b3' 
  AND token = 'cEZmi7xWGNskDmmNXRubi1KTVbKbLCm4q+vgIhc+hmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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