SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b51cfc3426c52d001e66c519a658269ce59b98df216dfabe65eaddacac02e4b' 
  AND token = 'e9G7bFvH6C7PpSZF0f6A8FLBwPyH+P0sPRupR8fe49I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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