SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1feb0f90785fa1610c0b6640d4e90fd50681ff0df986aa3adb343f492cf176fd' 
  AND token = 'y/oYtAQTk3reqgShh5797lhSYkyYH0Zeu7OuNo4NZD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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