SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7e8d8dec734aef43439f60285a98d1379d467a017f4c1d4ca53a018408a96bc' 
  AND token = 'AAQEYxlRLaFgmQ9LnWD6OExCPidUsBp8KuwtwgnWWHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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