SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2560fc17e460071f57e2db8e8ba53d3174903f3f5a91478fe5ee17852189698' 
  AND token = 'iNssKUc/XNeyVZ/JgFC9hj2+8rxyHtjYT3SgRSrTAuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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