SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9afb37d6b99253a7c36e95b74d9889db84bdfd7785fd83b745667b0fb1ca2eb' 
  AND token = 'qYDvJd0Ih5MV8AcSEZuQL5Dp0wB3CTQCy0PSDA25npk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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