SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b20b3be87001491f8740d37f145842291c6d93af579e816858ad2cd56db1fad' 
  AND token = 'V7bNhQ3He9GsmWOBPqxwEMKc/u/gBhOquvGza8/cC8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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