SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db1f7d676307f461362e1d2a8509c111dde179965d1fe46c6b4cbb59572bf78' 
  AND token = 'g81ifiUBcMUYvLOmYvXX5mmOZKu2KUXczzjBHQGAn7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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