SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '588ab78790f4d1968997f0cfee15c7602c992008780d5e561789fae2f2ff007d' 
  AND token = 'l2IRGOkYpuEDAL9j7FmBnjzZ4r5Go5mXesHIK+8wLDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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