SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e021eec5facc4beae2f20cb6d2476697844c70367f54b7edc56a2074b35370ea' 
  AND token = 'WZq4sk/xVmkBtb5jShSWS4IdvvLjacf+yhX/cksB5UE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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