SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '834ca2e683b0517652c3cce279ccd78e1b8f45cdb712b32320012b5a0ecadbf0' 
  AND token = 'c5i1vxeXYr+qtTJGZ7YQ3WaI+tQ1YZiE1ZXPcd2LAIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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