SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f436b7aa70c9adb3c2668d9e60b4ae339be992968592730189ad76f688f50e5b' 
  AND token = '6KQ+aPrhSZRz+Z1hfqJM0XDLRpwzWzYR6SJzFPfP0Qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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