SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b668f013c08cf3f14f81285ba936e1d5006178629eac99efcccba1df5665854' 
  AND token = 'Mf13mEB+gCvqsomQgUD94d9SByryDRReiGiiTsPDA8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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