SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83cd97709b6d79e367667cf501238e91dd046e7870372f040577d7a5b999b0bb' 
  AND token = 'GjrhJaphsa1q8H4uCFz/mv+awYY1ptSnUKFmzW1+OSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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