SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e10e568bfceaec04549be8b8320a3be8d5da6c88ae66cea206d96202428fb300' 
  AND token = 'BdSR+mSGL6hwL1pCgXlC3PrVayHb/zvCGCbbZn7NBuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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