SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a39afe7d3c2979a865b8f3a583a496245f0d841980c0dbe9af5196abdd3a833' 
  AND token = 'kYyr86I9ZmJ9vgeqEXCtlXgce6KWP8K+k39FViqb75Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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