SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fd989068eace8bb397ca01b9284653fd59e25cd2013e8557af3f6e30b519c1c' 
  AND token = 'JU5kDR554hmjBhZz3JBnRajpUUixUeelVubmITHbrho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}