SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6723989a9bf3220e14e6444dc314a3dc314f8680bd153a861baa3fb52d5a22e6' 
  AND token = 'ShdPSwg/gNbsyv2retnvYMS0f5CvOsoNwN1Tiahkn28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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