SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6111d856830cbbd576700cd30a6447019518aad07ef7fa2d3875eaa0645e20d4' 
  AND token = '81v2YJ+qfbMQT8mXOGj1vCbOVreaCAubDYhxBC1akUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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