SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852ed91864851ea4fd4712b32269d631ff4dcf4bc97d5f06ce706d8309efa8e3' 
  AND token = 'SuYDHjVPxnpzEDxJkr5GGvIKBj+PAFlUTR5rpCPQVOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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