SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9386818d9293463a6e42d02af614fd8fdd3ebc0ee5b92899d50585196e0d0592' 
  AND token = 'JOu8ShA2ALRBCPgpVgWaJsxhrmI2UTEgjv9BYLmIAnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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