SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3830f90f344db8456f85afa1ff51d7e3a61e1d384c54b7c4b3d5e10ffc0dcc9c' 
  AND token = 'Q0RSlHqjxqYRiPXT9kjcLG4mpR9wesGbFLu+8Ir87A8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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