SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36c7f96c6e738d0972c577900607189b022c6a7b511f550435f8c5dea622959b' 
  AND token = 'mv0vl47gT0cMEyKhr7ThJu27o3b5psH8HtNxFRCgDsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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