SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0c843be9226342a9477e0b99c208f02ab54a1ffea4141e22b5c94f290be2d1e9' 
  AND token = '0QiZaMlAx0WLRjG2woN3h7o6d2iuiF8oywRUCsNvz2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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