SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99e04ea2dfbd6dbe7e7b5ac0e36e4a5e8c247ff186fe6de3700a8b00e652f011' 
  AND token = 'SeAZRrNkCRWFjfLEGaVMr+xv4/ZxAdsaGTsoqIHiSvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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