SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7124575b40e336f72c007bd8b4307c872827cdc1f9f626b9757e34a81593fe40' 
  AND token = 't8FIlbvUgAFs+BUbTREiePTuXHz+7l7qfMUIpzR+QwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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