SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c6bc74b847c7a45d4f2659eaff87cb1c311054ff0ed726dde6f063d2d34a612' 
  AND token = 'cp2LGC5nx4ZVzTarkgQdlJUJHv+MBeJybeFEGBtZlGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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