SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6840fc35303715af412c7a6a9174c59b3e0426379cfce1b63f2a7760489fb3e5' 
  AND token = 'Ws3vIj1ZlMhFSqPKrLCF3BGNinXo83ZisG3KPL/lGq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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