SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a1c5ae6c2008f8a28a7a631ec7e0d286980090817827026334afe0b39c6b6f3' 
  AND token = 'vU9wYFTygtDxZs/uA9U4EsoFtiefh3zJgq9V+1ZGGGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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