SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '840a1d4a1a4b21e58635d638e089e230956617eb45a544327e071fcc11ecf9cc' 
  AND token = 'ZCCaPXQfI5YUYNrmM5vP/Lth+7GxDf0BnfJTdyj1LCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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