SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3e6445ae5d65ed6fa9513506870648f3018e60df996b3a02564d44b28f99c3d7' 
  AND token = 'gW5rFhPtU0AH44l4/w4ad3H1f6Nl6+h4vSundjfLLIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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