SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f082ea6ee9251a996fdb9cc9d6f1c74816124c167cfbf50f2e0177bf027d5ee6' 
  AND token = 'mKVQgp2w45YGqV3MwQwbIya2xtZvBK6XHyhYbUkyrR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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