SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8dda9e7c5575f303df9b1cac514078f3a887956e5a135f1452d4ef5a719fdba' 
  AND token = 'PhccuQuUKzxh9X8B3fCFYuzA3+mpG4E8dxoNU55S+Mo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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