SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c018bad777a007e54479caa7726a885ed5b922bb28858cc3237d9714aef3c233' 
  AND token = 'cWgZwaTnV2Xoho/KKAtss17Utzp3IrWtIeoO6EfcSUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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