SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49340a42ff70e9ee7dc74cfe09049507b3da55ec93dc56cfc660c36ed82b187c' 
  AND token = 'LbM/+9nuH1R9QYHwWSVjKBGTet+6ykhv1cYMphLXzQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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