SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f747d5842593e8b8406474106a520b63cfc284fe9d796896004a4cc6826ca3c' 
  AND token = 'LhEWEAsGUxsypRmBcG3BN61LLmjL4Kvq7cHPbj8xz4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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