SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cde777b09a5ec799a6a4a178662fb073ad7ea09d0fd3dda27dae54a7840e284' 
  AND token = '9dKjHLl024G/PNY4dW3+v+8ZRELa3fYInuvrKiiR5wQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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