SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ad69de1ad34f5f340c4407988a6ab062b23ee6c46cc854211024e7afa85db92' 
  AND token = 'clI3JYDoWrAomEPz1ftVu4tTGirRjx8RsMuIfb3v53A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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