SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d626e449e829de7e919eb98624fa6de29ae8263275e4408f7985ffcac729ea4' 
  AND token = '8b2OMrXhLHaCJsYFrCBsJKV7S/LhOoiRnkbtx8p6to0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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