SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c46245a011100307336a9564a78b1d4957f1c2d797f7ab20782b575f659a0a3' 
  AND token = 'EKuZAL1Rg0EvJQCzRzAqpG/blPWIunHfRIN7y3M/wKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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