SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a644d29efc4026dccb4febc002c80802647b8d0375d75cca156bce53222f9e05' 
  AND token = 'LyFlC/FkwtzRPeF676wcvzwXphNymNuhHqF7SLgbHng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}