SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12a8fdf2246355efc4569239f577421f6fb30208fb3e819cab1b6af00b6682fb' 
  AND token = '3wYksq0lpw6aQ7f35cZtUTn/veqNoy8MbteBrIItOeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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