SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5651836cde4f53130718d102a410379f3409ecc456fa2d56e2eaa546cdf87331' 
  AND token = '+EQVxHKXVFloSrU1e8ItJ+boGleOgbZPImpZ2WWdaVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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